poor man's square broach

A new member was asking how to drill square holes so I thought I would share a process that I have used successfully in the past

for instance to make a 5/16" square hole in soft material or even in mild steel as long as it is not too thick I have taken a 7/16" NC starting tap and ground it square. the teeth will broach out the material to make a square hole. Care must be taken when doing it like this because the 60° cut angle is wrong for this application
press the modified tap through the holes
here is a drawing of how the tap would look
Ideally you would use a 5/16 sq piece of tool steel ground to the shape of a broach
like this

All "old " mecanicians have a big tin bean can where we put all the "can be useful sometimes later"…
And when you need a small piece of very good steel to make a new centering pin for example, what better than a broken tap.

It'd not hoarding. It's the fuel of creativity waiting for sparks from your mind.
It works like this: A pile of treasure fills all available flat spaces. In recognition of this problem you use some of the stuff to create storage in the air volume above the other stuff. Cardboard, yellow carpenter glue, cutting tools, assorted spring clamps and a can of left over paint are needed. Now you have new flat space to fill.
Repeat the cycle; but take time to mark things for ID and make dividers for the little containers. Show someone your accomplishment and tell them it's not hoarding, it's creativity
2nd repeat cycle. Attach stack of storage containers to wall to keep gravity at bay.
Go into Michaels or Hobby Lobby and come out with nothing but some new storage boxes that were on sale.
You are beginning to feel artistic. Buy another can of mismatched paint; but a different color.
3rd cycle. There is no longer any space on the workbench except where the vise is mounted. You find a scrap piece of plywood and attach a stringer board to the back that will allow this new little mini-workbench in the jaws of the vise. Voila!! New flat space in thin air!
People you know are beginning to notice ..............